I don't care about superhero movies, so I haven't seen any of the Marvel or DC movies, yet I still know they exist and sometimes I know which one is being promoted right now. If I got stuck at a table somewhere with someone who is a big fan of them, we could have a conversation. It'd mostly consist of me asking questions, but that'd work fine, because as a fan he'd have opinions to share. Same thing with sports or anything, really.